Electrochromic thin film state-of-charge detector for on-the-cell application

ABSTRACT

A tester for use in determining the voltage and state-of-charge of a battery. The tester can be permanently mounted on the battery and employs an electrochromic cell which changes visual appearance, for example, color or intensity of color when electrically connected across the terminals of a battery. The electrochromic cell undergoes an oxidation/reduction reaction on direct application of the DC potential of the battery. The color of the electrochromic cell can be compared with a color comparison chart to determine the condition of the battery. The tester can be permanently electrically connected to the battery or, preferably, can be connected momentarily to determine the state of the battery.

This is a continuation of application Ser. No. 07/648,080 filed on Jan.31, 1991, now abandoned.

BACKGROUND OF THE INVENTION

Since the original manufacture of dry cells or batteries, a user cannottell from looking at them whether they have little useful life left orwhether they are fresh. A completely discharged battery and a new onepresent the same physical appearance. To determine the usefulness of abattery, one would think that one could simply put the battery into adevice and operate the device. Very few devices, however, work with onlyone battery and if a new battery and a discharged battery, or a nearlydischarged battery, are put into a device such as a flashlight, theflashlight will glow very dimly, if at all. The conclusion, then, isthat the batteries are all defective and should be replaced when, infact, one of the batteries might be a fresh battery.

In order to test the cells, one can use relatively expensive testingequipment such as a voltmeter or an ammeter but this is an inordinateexpense in comparison to the cost of a new set of batteries.

There are other proposals for testing batteries. For example, U.S. Pat.No. 4,723,656 issued Feb. 9, 1988, to Kiernan et al. discloses ablister-type package for new batteries with a battery conditionindicator built into the blister portion of the package. The blister canbe deformed to place the tester across the terminals of a battery to betested. A thermochromic liquid crystal material is employed in thetester in combination with a wedge-shaped resistive element. As thecurrent flows through the resistive element, a thermal front will moveaway from the narrowest portion of the wedge to an extent depending onthe capacity of the battery. The effect of the thermal front moving canbe seen in the liquid crystal layer in thermal contact with theresistive element.

Several patents have been issued to Robert Parker, for example, U.S.Pat. Nos. 4,702,563; 4,702,564; 4,726,661 and 4,737,020 relating to theuse of a heat generating pattern on a flexible substrate in combinationwith a thermochromic liquid crystal layer to determine thestate-of-charge of a battery. Attempts have even been made to view thecontents of the cell while in use and to detect a color change in theworking components of the cell to determine the state of the cell, forexample U.S. Pat. No. 4,497,881 issued Feb. 5, 1985, to Bertolino. U.S.Pat. No. 3,667,039 issued to Garfein et al. on May 30, 1972, disclosesthe use of liquid crystal materials in a closed cell having either ashaped electrode or a shaped cell in order to provide a field gradientacross the liquid crystal material. The cell is then connected acrossthe terminals of a battery and the state of the battery is determined bynoting the location of a visible gradient in the liquid crystal materialand reading from an accompanying scale the status of the battery.

U.S. Pat. No. 4,835,476 issued to Kurosawa discloses heat sensitive dyesystems using organic materials such as crystal violet lactone incombination with other reactive materials to form compositions whichdecolorize on application of the heat produced by current flowingthrough a resistive element connected between the terminals of abattery. When the coating material decolorizes, a scale beneath thecoating becomes visible indicating the status of the battery.

It can be seen from the above discussion that most attempts in the pasthave used thermochromic materials, that is, materials which undergo achange in color or color intensity on the application of heat. Sinceheat is used to change the color of the material, it is important thatthe heat not be drawn away from the measuring device. It has, therefore,not been practical to employ such devices attached directly to the drycell or battery to be tested. The large thermal mass presented by thebattery acts as a heat sink drawing the heat away causing the measuringdevice to read inaccurately. A battery condition tester has long beendesired for incorporation on the cell or battery rather than on thebattery package. Such an on-the-cell tester would be more convenient forthe customer since it would be an integral part of the cell or batteryand would not be discarded with the original battery package.

SUMMARY OF THE INVENTION

In accordance with the present invention, a combined battery and batterytester is provided. A housing contains the active components of thebattery and has a pair of external terminals. A tester for the batteryis disposed on the housing. The tester includes a working electrodecomprising an electronic conductor and an electrochromic material thatundergoes a visible change as a result of a redox chemical reaction. Anionically conducting electrolyte is in contact with the workingelectrode. A counter electrode is in electrical contact with theelectrolyte layer. The visible change in the electrochromic material isvisible through the working or counter electrode. A pair of electricalconductors are provided for connecting the working and counterelectrodes to the external terminals of the battery for testing thebattery.

A measuring device is provided for detecting and measuring thestate-of-charge of a cell or battery. The device employs anelectrochromic material. The electrochromic material changes color(change in light absorption) as the material changes oxidation state, aredox-type reaction, under the influence of a DC potential applieddirectly to the electrochromic material. The electrochromic material maybe a solid, a solid in solution or a liquid in a liquid solution.Solution devices are sometimes referred to as electrochemichromicdevices. The measuring device can be applied to the battery housing, thelabel on the housing or the end covers to measure the state-of-charge ofthe cell.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic elevational view of the battery tester of thepresent invention accompanied by a scale for comparing the color of theindicating device and determining the state of charge of the cell;

FIG. 2 is a sectional view taken along the line II--II of FIG. 1;

FIG. 3 is a perspective view of a battery having the measuring devicemounted on the housing;

FIG. 4 is a plan view of an end cover for a battery showing a pattern ofmeasuring devices;

FIG. 5 shows an end cover with a single measuring device;

FIG. 6 is a plan view of an end cover having an elongated arcuatemeasuring device along with a battery status color scale;

FIG. 7A is a simplified schematic of the electrochromic cell connectedfor an open circuit test of a battery;

FIG. 7B shows the simplified schematic of FIG. 7A with a switch added toisolate the measuring device from the cell;

FIG. 8 is a simplified schematic of a closed circuit measuring device;

FIG. 9 is a simplified schematic of a device employing a resistive loadwhich is also an electrode of the electrochromic cell;

FIG. 10 is a partial elevational view of a label for a battery includinga printed battery condition testing device; and

FIG. 11 is a partial sectional view showing the label and batterycondition testing device of FIG. 10 applied to a battery.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a typical electrochromic state of battery chargedetermining device is shown and indicated generally by the number 20.The device has a transparent cover 21 for containing the severalcomponents of the measuring device. The cover 21 has a window or topsurface 23 through which the electrochromic material 25 can be viewed.Electrical conductors 27 and 29 extend from each end of the measuringdevice. The conductor 27 is shown as being of indeterminate length andhas a terminal 31 for connection to an external terminal of a battery.Likewise, the conductor 29 is shown of indeterminate length and has aterminal 33 for connection to the opposite terminal of the battery to bemeasured. A switch is schematically illustrated at 35 which can be usedto connect the measuring device 20 across the terminals of a batterybeing tested. A color scale 37 can be mounted on the housing of thebattery 20 for providing a ready color comparison for the electrochromicmaterial to determine the state-of-charge of the battery.

In FIG. 2, the state-of-charge indicator 20 is shown mounted on abattery 39, only a portion of which is shown. In the example shown here,the indicator comprises a cover 21, a counter electrode 26, an ionicallyconducting electrolyte layer 24, and the electrochromic workingelectrode which comprises conductive electrode 41 and electrochromicmaterial 25. Counter electrode 26 can be part of the battery label orthe battery housing. An electronically conductive electrode 41, which isat least partially optically transparent, is coated on the inner surfaceof cover 21. Alternative modifications of this construction will beapparent to those skilled in the art. For example, one or moreelectrochromic materials, which can be the same of different materials,can be deposited or coated on both the transparent electrode 41 andcounter electrode 26, which can be non-transparent. A furthermodification involves coating or depositing an electrochromic material25 on electrode 26 which then becomes the electrochromic workingelectrode. Further modifications of electrochromic cell construction canbe found in Proc. Symposium on Electrochromic Materials, Vol. 90-2, M.K. Carpenter & D. A. Corrigan, Editors, The Electrochemical Society,Princeton, N.J., 1990, or in Large Area Chromogenics: Materials andDevices for Transmittance Control, C. M. Lampert and C. G. Granqvist,Editors, Optical Engineering Press, Bellingham, Washington, 1989.

The transparent electronic conductor 41 can be made of a thin metallayer or metal oxide such as doped substoichiometric oxides of indium,tin, cadmium or zinc, e.g., a fluorine- or antimony-doped tin oxide, aslong as the transparent conductive material is compatible with thecomponents of the electrochromic cell. The preparation and applicationof such transparent electrically conductive films is well-known in theart. A description of such transparent electrical conductors is given inthe article by Niall R. Lynam entitled "Transparent ElectronicConductors," Proc. Symposium on Electrochromic Materials, Vo. 90-2, M.K. Carpenter & D. A. Corrigan, Editors, The Electrochemical Society,Princeton, N.J., 1990.

If the electrochromic materials used in the cell have suitableelectrical conductivity, they can function both as one of theelectrically conductive electrodes in the electrochromic cell and as thematerial undergoing the redox reaction and exhibiting color developmentor change.

The electrolyte materials suitable for use in the electrochromic cellmay be inorganic or organic, liquid or solid, or combinations thereof,e.g., polymer electrolyte materials such as poly-2-acrylamido-2-methylpropanesulfonic acid [poly(AMPS)].

The cover 21 can be made of any of the well-known transparent plasticmaterials such as polyvinyl chloride, polyvinylidene chloride,polyethylene, polyesters and the like.

The electrochromic material used in the state-of-charge measuring cellcan be either an organic or an inorganic material which changes color orcolor intensity, that is, optical absorption, on application of a DCpotential. The active material in the electrochromic cell undergoes anoxidation/reduction reaction, commonly referred to as a redox reaction,in order to develop or change color. The optical absorptivity of thecell is controlled by driving an electrode from one state to anotherwith an external power source.

In some cases, the electrochromic material itself may not undergo theredox reaction but may react with a redox product to produce a colorchange. An example of such a system is the production of OH⁻electrochemically followed by the reaction of the OH⁻ with an organic pHindicating dye to give a color change. This type of electrochromicsystem is the subject of U.S. Pat. No. 3,280,701 by J. F. Donnelly andR. C. Cooper.

Electrochromic materials which show a very large change in extinctioncoefficient are preferred so that very little electrode material (andhence a very small amount of current) is required to produce a visiblecolor change. This is in contrast to thermochromic liquid crystalmaterials which develop a change in color when a phase change takesplace such as going from a solid to a liquid crystal phase.

Inorganic electrochromic materials are represented by WO₃, MoO₃, TiO₂,SnO₂, Cr₂ O₃, NiO₂, MnO₂, Mn₂ O₃ and Prussian blue which are typical ofmany well-known solid inorganic electrochromic materials. Such materialshave been studied extensively in applications such as optical filters,one-way glass, and variable reflectance mirrors. These materials can beused in a solid form as a coating applied to the transparent conductivecoating on the interior of the cover of the device.

EXAMPLE 1

A tungsten-containing compound was prepared by electrolysis of anaqueous mixture of potassium tungstate, K₃ WO₄, and oxalic acid, H₂ C₂O₄. The compound was deposited by electrolysis onto an opticallytransparent electronically conductive coating previously deposited on aplastic substrate. This compound can function in the same manner as WO₃which, as pointed out above, is a well-known electrochromic material butwhich cannot be readily obtained commercially as a film. The deep blueelectrochromic films obtained by the K₂ WO₄ --H₂ C₂ O₄ reaction could becycled in 0.1N sulfuric acid and appeared to be stable after 200 cyclesat 3 Hz between 0.0 to -0.4 volt vs a saturated calomel referenceelectrode (SCE). This material is colorless at potentials more positivethan -0.1 volt and blue at potentials more negative than -0.3 volt vsSCE. The intensity of the blue color increased as the potential wasdecreased to -0.8 volt.

Representative of solid organic electrochromic materials include manymacrocyclic and polycyclic materials such as metal phthalocyanines,polypyrrole and polyaniline and common dyes and redox indicators such asnaphthol blue black and N,N'-diphenylbenzidine. These materials can beapplied in solid form as a film on the transparent conductive layer onthe inside of the cover of the device.

One such solid material, N-Benzylaniline, was selected as an example ofan organic material which can be polymerized electrochemically toproduce conductive electrochromic films.

EXAMPLE 2

The electrochromic electrode was prepared by electrolysis of a 0.1MN-Benzylaniline in 1.0M phosphoric acid as described by Nguyen and Daoin J. Electrochem. Soc., 136, 2131 (1989),Poly(N-Benzylaniline/(Poly(AMPS)/WO₃ Solid-State Electrochromic Cell.The film prepared by this method could be cycled in 0.05M sulfuric acidfrom a deep blue/green at 0.8 volt to a transparent yellow at 0.2 voltvs SCE reference. This electrode was cycled 200 times at 3 Hz withoutapparent degradation.

The working electrode comprising conductive electrode 41 andelectrochromic material 25 of the electrochromic cell shown in FIG. 2 isplaced so that it is in contact with an ionically conductive layer 24.This layer 24 is also in contact with the counter electrode. Since thestate-of-charge measuring device is to be applied directly to thebattery housing or end cover, the counter electrode does not have to betransparent.

The counter electrode 26 in the electrochromic cell is an electronicconductor and can be a metal, a metal oxide or an organic conductor. Itcan also be made of, or contain a coating of, an electrochromicmaterial, or a combination of the aforementioned materials, e.g., acoating of an electrochromic material on a metal or a metal oxide. Themain requirement for the counter electrode in the electrochromicstate-of-charge indicator is that it poise the overall electrochromiccell potential at the correct level for the cell or battery to betested. The potential may be the result of an electrochemical coupleintentionally added or an adventitious impurity.

In addition to the systems using solid electrochromic materials and anelectrolyte, as mentioned above, the use of systems employing a singlelayer functioning as both the electrochromic material and theelectrolyte, i.e., electrochemichromic systems, is contemplated. In thismodification, the electrochemichromic material includes an anodiccomponent and a cathodic component which undergo oxidation and reductionat the respective electrodes. Both the anodic and cathodic componentsmay contribute to the observed color change and each electrode mayfunction as a "working electrode" and a "counter electrode." Bothelectrodes (the electronic conductors at which the electrochemicalreactions take place) can be made of the same or different material;however, at least one electrode must be at least partially transparentto permit observation of the visible change in the electrochromicmaterial. Materials such as standard pH or redox indicators, e.g.,phenolphthalein, methyl violet, ethyl red, methylene blue,N,N'-diphenylbenzidine, naphthol blue black or N,N-dimethylindoanilinecan be used. Further examples of such electrochemichromic systems can befound in U.S. Pat. No. 4,902,108 issued Feb. 20, 1990, to Harlan J.Byker, which is incorporated herein by reference. These includeN,N,N',N'-tetramethyl-1,4-phenylenediamine;5,10-dihydro-5,10-dimethylphenazine and N,N',N"-trimethyltriphenazinoxazine. Phenolphthalein, methyl violet or ethylred provide an indicative color change through the oxidation andreduction of the solvent (e.g., H₂ O). As described above, the indicatormaterial does not itself undergo a redox reaction but instead reactswith another species, e.g., protons from water, which are produced bythe redox reaction.

When the electrochemichromic materials do not form suitably ionicallyconductive solutions, a small amount of a compatible electrolytematerial can be added. The electrochemichromic solution can also bethickened by using polymeric thickeners such as polymethylmethacrylate,polyethylene oxide, poly-2-acrylamido-2-methyl propanesulfonic acid[poly(AMPS)] or the like.

Referring to FIG. 3, a typical C or D size dry cell battery is shown andindicated generally by the number 50. A typical battery has acylindrical housing 51 and an end cover 53 in contact with positiveterminal 55. The opposite end cover is indicated by 57. On the side ofhousing 51 is an electrochromic state-of-charge tester indicated by thenumber 60. The battery testing device can have one or moreelectrochromic cells, for example three cells, similar to cell 20 ofFIG. 1. Cell 64 can have an electrochromic composition contained thereinand be poised to indicate a fresh battery. Cell 63 can be of a similarconstruction, however, having a different electrochromic cell materialand being poised to indicate a good condition of the battery, while cell65 is again of similar construction with a different electrochromicmaterial which indicates that the battery should be replaced. Cell 65 isconnected to the negative end cover 57 by means of a conductive strip ofmaterial 67 which is folded under and has a contact 69. At the oppositeend of the tester, a conductor 71 completes the connection to thepositive terminal of the battery. Alternative means of making contactbetween the electrochromic cell or cells and the battery terminals maybe used. For example, one terminal of the electrochromic cell can be indirect contact with one of the battery terminals.

As shown in FIG. 3, the state-of-charge indicator is continuously incontact with the negative and positive external terminals of thebattery. When used in such applications, it is preferred to use a solidstate electrochromic cell, the layers of which are applied as coatingsover the transparent conductor on the interior of the electrochromiccell cover. Solid state electrochromic cells tend to draw substantiallyless current than solution electrochromic or electrochemichromicmaterials. When the latter materials are used, it is preferred to use asuitable switch such as switch 35 (FIG. 1) to momentarily connect thebattery testing device across the terminals of the battery and, afterthe reading is complete, the switch should be opened to electricallyisolate the battery from the testing device.

FIG. 4 shows the end cover 75 of a battery having a terminal 77 andthree electrochromic battery state-of-charge indicating devices 79, 81and 83. The individual electrochromic cells are already connected to oneterminal of the cell. A conductor, such as conductor 85, is electricallyinsulated from end cover 75 and contacts the opposite electrode withinthe electrochromic cell and the other external terminal of the battery.A similar contact means can also be provided for cells 81 and 83 (notshown to simplify the drawing). Electrochromic cells 79, 81 and 83 canbe substantially similar to cells 64, 63 and 65, as shown in FIG. 3.Again, if a suitable solid state electrochromic cell is used, the cellscan be left in continuous contact with the external terminals of thebattery. If a solution electrochemichromic cell is used, it is preferredto provide a switch to electrically isolate the testing device until itis actually to be used for testing.

FIGS. 5 and 6 are similar to FIG. 4. In FIG. 5, end cover 85 has asingle electrochromic cell 87 directly connected to one battery terminaland connected by a suitable circuit means 89 to the opposite terminal ofthe cell. FIG. 6 shows an end cover 91 with an attached electrochromiccell 93 electrically connected by a suitable conducting means 95 to theopposite terminal of the battery. The electrochromic cells, as shown inFIGS. 5 and 6, would preferably have an associated color scale 100 onthe battery label. The color scale has three colored portions 101 toindicate a fresh cell, 102 to indicate a good cell and 103 to indicate acell which should be replaced. The person using either one of thebattery state indicating devices of FIGS. 5 and 6 merely observes thecolor visible in the cell 89 or 93 and compares it with the color dotsof the scale 100 to determine the state of the battery.

As indicated above, the battery state indicating device can be incontinuous electrical contact with the external terminals of thebattery. Since the testing device does draw current, it is preferred tohave some type of an external switch to isolate the testing device fromthe battery.

The state-of-charge indicating device can be used in either an opencircuit or a closed circuit mode. In the closed circuit mode the voltageof the battery is tested under load. FIGS. 7A and 7B show a typical opencircuit configuration for testing a battery. In FIG. 7A, electrochromiccell 130 is connected in series with battery 131 to be tested. In FIG.7B, electrochromic cell 130 is again connected to battery 131; however,in this circuit a switch 133 is used to take the electrochromic testingdevice out of the circuit so as not to discharge the battery. It can beseen in the open circuit test that no load other than the electrochromiccell itself is placed across the terminals of the battery being tested.

Referring to FIG. 8, this figure represents a typical closed circuittest in which a load resistor 135 is placed across the electrochromiccell 130. The battery 131 is again connected for testing or isolated bya switch 133.

In the open circuit measurement circuit, as shown in FIGS. 7A and 7B,the electrochromic cell should be poised to sense the range of voltageproduced by the battery 131. When a different voltage range is producedby different types of batteries, different electrochromic materials canbe used in the electrochromic cell. In the circuit of FIG. 8, the loadresistor 135 can be varied to match the electrochromic cell 130 to thepotential produced by the battery 131 in addition to selection of theappropriate electrochromic material. The load resistor 135 can be formedusing an electrode having intermediate resistivity such as thetransparent electrode on the inside of the cover of the electrochromicdevice. Such an electrode can be shaped or patterned to vary theresistance and serve as the load along which the potential decreases.

The selection and matching of the voltage range of the electrochromicmaterial can thus be largely avoided by using a testing circuit such asthat shown in FIG. 9 in which the resistivity of the electrode, e.g.,the transparent conductive electrode 41, provides the resistive loadand, in combination with the electrochromic cell 130, acts a voltagedivider. In this cell, the voltage drop across the electrodes of theelectrochromic device varies from the closed circuit voltage obtained atthe left end of the electrochromic cell, as shown in FIG. 9, to a lowervoltage (possibly zero volt) at the other end. With this type ofindicator, the state-of-charge of the cell is determined by the positionof the color in the electrochromic device.

In an additional embodiment of the tester of the present invention,referring to FIGS. 10 and 11, the several components making up theelectrochromic cell can be applied to the label, indicated generally by140, during the label printing process where appropriate graphics 142are applied to the label. For example, the electronically conductivemembers of the electrochromic cell, e.g., the conductive electrodes 26and 41 and their conductive connective members to the battery, can beprovided by various means such as by printing a conductive pattern on alabel substrate using conductive ink or paint. Alternatively, conductivepatterns can be formed on a conductive substrate by etching techniquesto remove unwanted portions and by providing (e.g., by printing)suitable electrical insulation where needed. The solid electrochromiclayer 25 can also be printed. The electrolyte layer 24 orelectrochemichromic layer (a combination of 25 and 24) can be printed asa solution and then cured or dried. That electrically conductive member,e.g., member 41, through which the electrochromic material can be viewedcan be printed in the form of a grid or other open pattern or can be avapor-deposited optically transparent material.

The label and tester can be prepared so that one electrode of the testeris in electrical contact with one external terminal of the battery. Inan embodiment of the tester where the label is made up of severallayers, including a metallic layer, the metallic layer can serve as aconductive element or contact to the electrochromic cell. Eitherelectrical conductor 27 or 29 can be printed on the label so that itterminates near one external terminal of the battery without makingelectrical contact. The other conductor can be printed so that it willmake electrical contact with a terminal of the battery when the label isapplied. The open circuit can then be closed by bridging an electricallyconductive metal article, even the positive external terminal of asecond battery, between the conductor on the label and the end cap toactivate the tester.

In the manufacture of the label and battery voltage tester, it ispreferred to use a web of the substrate material which can hold manylabels and run the web through suitable printing operations or coatingoperations where the graphics for each label can be applied to the webalong with each layer of the tester. After the label and testers havebeen applied, the web of material can be run through a suitable punch ordie cutting operation to separate the individual labels from the web sothat the labels can be applied to batteries in the finishing of thebattery during the heat shrinking of the label.

From the above description it can be seen that a device can be providedfor testing the state of a battery which can be applied to the housingor end covers of the battery and left in place at all times. Since thedevice does not rely on heat, the thermal mass of the battery will notaffect the operation of the device. When the electrical circuit for thetesting device is completed, the electrochromic material will changecolor indicating the state of the cell.

Though the invention has been described with respect to a specificpreferred embodiment thereof, many variations and modifications willbecome apparent to those skilled in the art. It is therefore theintention that the appended claims be interpreted as broadly as possiblein view of the prior art to include all such variations andmodifications.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows.
 1. A battery having firstand second external terminals, and a label and a battery conditiontesting device wherein said battery testing device comprises;a firstelectrically conductive pattern and a second electrically conductivepattern spaced apart from said first electrically conductive pattern; anelectrochromic material in contact with at least one of said first andsecond electrically conductive patterns; an ionically conductiveelectrolyte contacting both of said electrically conductive patterns;said electrochromic material, said ionically conductive electrolyte, andat least one of said first and second electrically conductive patternsbeing applied to the label during the label preparation process; and afirst electrical conductor for electrically connecting said firstelectrically conductive pattern to said first external terminal on saidbattery, and a second electrical conductor for electrically connectingsaid second electrically conductive pattern to said second externalterminal on said battery; wherein said electrochromic material undergoesa visible change as the result of applying a DC potential to saidelectrochromic material with power supplied from said battery.
 2. Acombination battery and battery tester comprising:a housing containingthe active materials of a battery; a first and a second battery terminalof opposite polarity on said housing for providing electrical connectionwith said active materials in said housing; a battery condition testingdevice disposed on said housing, said device including; a firstelectronically conductive member which may be placed in electricalconnection with said first terminal, a second electronically conductivemember which may be placed in electrical connection with said secondterminal, said second electronically conductive member spaced apart fromsaid first electronically conductive member; a layer of anelectrochromic material disposed between said first and said secondelectronically conductive members, said electrochromic material being inat least one of electrical contact and ionic contact with at least oneof said first and said second electronically conductive members; and aresistive load electrically connected in parallel with said batterycondition testing device, wherein said resistive load has a sufficientresistance so that said testing device is poised to sense the voltage ofsaid battery.
 3. The combination battery and battery tester of claim 2further comprising a scale which is capable of indicating the full rangeof the state of charge of said battery.
 4. The combination battery andbattery tester of claim 2 wherein said testing device is configured toenable determination of the state of charge of said battery by positionof color in said testing device.
 5. A combination battery and batterytester comprising:a housing containing the active materials of abattery; a first and a second battery terminal of opposite polarity onsaid housing for providing electrical connection with said activematerials in said housing; a label comprising a first label layer and asecond label layer, said label affixed to said housing; a batterycondition testing device adapted for disposing within said label, saiddevice disposed within said label affixed to said housing, said deviceincluding; a first electronic conductive member disposed on a portion ofsaid first label layer which may be placed in electrical connection withsaid first terminal, a second electronic conductive member disposed on aportion of said second label layer which may be placed in electricalconnection with said second terminal, said second electronic conductivemember spaced apart from said first electronic conductive member; alayer of an electrochemichromic material disposed between said first andsaid second electronic conductive members, said electrochemichromicmaterial being in at least one of electrical contact and ionic contactwith at least one of said first and said second electronic conductivemembers; and wherein said electrochemichromic material undergoes avisible change as the result of a redox chemical reaction induced bydriving at least one of said electronic conductive members from oneoxidation state to another with power supplied from said battery.
 6. Acombined battery and battery tester comprising:a housing containing theactive components of said battery and having a pair of externalterminals; a tester for said battery disposed on said housing, saidtester including: a working electrode comprising an electronic conductorand an electrochromic material that undergoes a visible change as theresult of a redox chemical reaction; an ionically conducting electrolytein contact with said working electrode; a counter electrode inelectrical contact with said electrolyte wherein the change is visibleas viewed through the working or counter electrode; a pair ofelectrically conductive members for connecting said working and counterelectrodes to said external terminals of said battery for testing saidbattery; and a resistive load electrically connected in parallel withsaid working electrode, said electrolyte, and said counter electrode,wherein said resistive load is configured as a voltage divider to matchthe potential of the battery to the potential of the tester.
 7. Abattery and electrochromic state-of-charge indicator for said batterycomprising:a housing for containing the active components of saidbattery; an end cover for each end of said housing forming the externalterminals for said battery; at least one electrochromic state-of-chargeindicator mounted on one of said end covers and in electrical contacttherewith; an electrical circuit means for connecting the oppositeexternal terminal of said battery to said electrochromic state-of-chargeindicator to apply a DC potential directly to said electrochromicmaterial of said electrochromic state-of-charge indicator to cause saidmaterial to change optical absorption as the result of anoxidation/reduction reaction induced by said directly applied DCpotential, the resulting visual appearance of said electrochromicmaterial indicating the state of charge of said battery; and a resistiveload at least a portion of which is electrically connected across saidelectrochromic state-of-charge indicator, and configured as a voltagedivider to match the potential of the battery to the potential of theindicator.
 8. A combined battery and battery tester comprising:a housingcontaining the active components of said battery and having a pair ofexternal terminals; a tester for said battery disposed on said housing,said tester including: a working electrode comprising an electronicconductor and an electrochromic material; an ionically conductingelectrolyte in contact with said working electrode; a counter electrodein electrical contact with said electrolyte; and a pair of electricallyconductive members for connecting said working and counter electrodes tosaid external terminals of said battery for testing said battery;wherein said electrochromic material undergoes a visible change as theresult of a redox chemical reaction induced by driving one of theelectrodes from one oxidation state to another with power supplied fromsaid battery and said tester is configured to enable determination ofthe state of charge of said battery by position of color in said tester.9. A battery and electrochromic state-of-charge indicator for saidbattery comprising:a housing for containing the active components ofsaid battery; an end cover for each end of said housing forming theexternal terminals for said battery; at least one electrochromicstate-of-charge indicator adapted for mounting on said end cover, saidstate-of-charge indicator mounted on one of said end covers and inelectrical contact therewith; an electrical circuit means for connectingthe opposite external terminal of said battery to said electrochromicstate-of-charge indicator to apply a DC potential directly to saidelectrochromic material to cause said material to change opticalabsorption as the result of an oxidation/reduction reaction induced bysaid directly applied DC potential, the resulting visual appearance ofsaid electrochromic material indicating the state of charge of saidbattery, wherein said indicator is configured to enable determination ofthe state of charge of said battery by position of color in saidindicator.
 10. The combination of a battery and a label for said batterythat includes a battery condition testing device particularly adaptedfor affixment to said battery, said combination comprising:a housing forcontaining the galvanically active components for said battery; a pairof end covers for said housing to complete said battery and to form theexternal terminals for said battery; a layer of material substantiallycovering said housing, said layer of material including on the outersurface thereof the graphics for forming a label; a first electricallyconductive material on a portion of said label forming a first electrodeof said battery condition testing device; a layer of electrochromicmaterial on said first electrically conductive material; a secondelectrically conductive material on said electrochromic material forminga second electrode of said battery condition testing device; anionically conductive electrolyte in contact with said electrochromicmaterial on said electrodes; and a pair of electrical conductors forconnecting at least one of said first and second electrodes of saidbattery condition testing device to said external terminals of saidbattery; wherein said electrochromic material undergoes a visible changeas the result of a redox chemical reaction induced by driving at leastone of said electrodes from one oxidation state to another with powersupplied from said battery and said testing device is configured toenable determination of the state of charge of said battery by positionof color in said testing device.
 11. A battery having a label thatincludes a battery condition testing device wherein:said battery hasfirst and second external terminals; and wherein said battery testingdevice adapted for affixment on said label, said battery testing deviceon said label comprises: a first electrically conductive material on aportion of said label forming a first electrode of said batterycondition testing device; an electrochromic material on said firstelectrically conductive material; a second electrically conductivematerial on said electrochromic material forming a second electrode forsaid battery condition testing device; an ionically conductiveelectrolyte in contact with said electrochromic material on saidelectrodes; and a first and second electrical conductor on said labelfor electrically connecting said first and second electrodes of saidbattery condition testing device to at least one of said externalterminals on said battery; wherein said electrochromic materialundergoes a visible change as the result of a redox chemical reactioninduced by driving at least one of said electrodes from one oxidationstate to another with power supplied from said battery and wherein saidtesting device is configured to enable determination of the state ofcharge of said battery by position of color in said testing device. 12.A combination battery and battery tester comprising:a housing containingthe active materials of a battery; a first and a second battery terminalof opposite polarity on said housing for providing electrical connectionwith said active materials in said housing; a battery condition testingdevice adapted for disposing on said housing, said device disposed onsaid housing, said device including; a first electronic conductivemember which may be placed in electrical connection with said firstterminal, a second electronic conductive member which may be placed inelectrical connection with said second terminal, said second electronicconductive member spaced apart from said first electronic conductivemember; and a layer of an electrochromic material disposed between saidfirst and said second electronic conductive members, said electrochromicmaterial being in at least one of electrical contact and ionic contactwith at least one of said first and said second electronic conductivemembers; wherein said electrochromic material undergoes a visible changeas the result of a redox chemical reaction induced by driving at leastone of said electronic conductive members from one oxidation state toanother with power supplied from said battery and wherein said testingdevice is configured to enable determination of the state of charge ofsaid battery by position of color in said testing device.
 13. A combinedbattery and battery tester comprising:a housing containing the activecomponents of said battery and having a pair of external terminals; atester for said battery disposed on said housing, said tester including:a working electrode comprising an electronic conductor and anelectrochromic material that undergoes a visible change as the result ofa redox chemical reaction; an ionically conducting electrolyte incontact with said working electrode; a counter electrode in contact withsaid electrolyte wherein the change is visible as viewed through theworking or counter electrode; a pair of electrically conductive membersfor connecting said working and counter electrodes to said externalterminals of said battery for testing said battery; and a resistive loadelectrically connected in parallel with said working electrode, saidelectrolyte, and said counter electrode, wherein said tester isconfigured to enable determination of the state of charge of saidbattery by position of color in said tester.
 14. A battery andelectrochromic state-of-charge indicator for said battery comprising:ahousing for containing the active components of said battery; an endcover for each end of said housing forming the external terminals forsaid battery; at least one electrochromic state-of-charge indicatormounted on one of said end covers and in electrical contact therewith;an electrical circuit means for connecting the opposite externalterminal of said battery to said electrochromic state-of-chargeindicator to apply a DC potential directly to said electrochromicmaterial of said electrochromic state-of-charge indicator to cause saidmaterial to change optical absorption as the result of anoxidation/reduction reaction induced by said directly applied DCpotential, the resulting visual appearance of said electrochromicmaterial indicating the state of charge of said battery; and a resistiveload at least a portion of which is electrically connected across saidelectrochromic state-of-charge indicator, wherein said indicator isconfigured to enable determination of the state of charge of saidbattery by position of color in said indicator.
 15. A battery having alabel that includes a battery condition indicator wherein:said batteryhas a casing and first and second external terminals; and said batterycondition indicator includes a series of films, said films beingincorporated into the battery label as an integral part thereof, andsaid indicator operates by having electrochemical activity occur thereinand comprises a display that undergoes a visible change as a result ofsaid electrochemical activity.
 16. The combination of claim 15 wherein aseries of said labels and integral indicators are prepared in the formof a web, individual labels and indicators integral therewith thereafterbeing separated, one from the other, and affixed to a plurality ofbatteries.
 17. The combination of claim 15 wherein at least one of saidlayers is printed.